Bronchoalveolar lavage changes the ultrasonographic and radiographic appearances of lungs in adult horses.

Overview

• This study investigates how bronchoalveolar lavage (BAL), a diagnostic procedure, affects lung ultrasound and X-ray images in adult horses being checked for equine asthma syndrome (EAS).
• The goal was to understand whether BAL changes these imaging results, which might influence diagnosis and treatment decisions.

Background

• Equine asthma syndrome (EAS) is a common respiratory condition in adult horses, diagnosed through clinical signs, fluid analysis from the lungs, and imaging techniques like ultrasound and radiography.
• Bronchoalveolar lavage (BAL) involves collecting fluid from the lungs for diagnostic analysis to assess inflammation and cellular content, providing important information to confirm EAS.
• However, BAL is invasive and could potentially change lung appearance on imaging, which might lead to misinterpretation if scans are done shortly after the procedure.

Study Design and Methods

• Type: Prospective observational study.
• Subjects: 32 adult horses suspected of having EAS.
• Procedure:
  • All horses underwent lung ultrasonographic (ultrasound) and radiographic (X-ray) exams before BAL.
  • The exams were repeated within 3 hours after BAL.
• Scoring:
  • Ultrasonographic and radiographic abnormalities were scored using already validated scoring systems, quantifying changes in lung appearance.
• Group Classification:
  • Horses were grouped into normal, mild EAS, or moderate/severe EAS based on clinical and cytological findings.
• Statistics:
  • Kruskal-Wallis test was used to compare scores between the different severity groups.
  • Wilcoxon signed-rank test was used to evaluate differences in scores before and after BAL within the same horses.
  • Significance threshold was set at p < 0.05.

Key Findings

• There was a significant increase in both ultrasonographic and radiographic lung scores following BAL across all horses.
• Ultrasound Images:
  • Significant increase in abnormalities was noted on the right lung side after BAL.
• Radiographic Images:
  • Significant increases in abnormalities after BAL were found particularly in the caudoventral and caudodorsal regions of the lungs.
• The extent of ultrasound score increase did not correlate with the amount of fluid recovered during BAL or the percentage of neutrophils found in the fluid, indicating that changes in imaging scores are not obviously related to the fluid sample quality or inflammation level directly.

Interpretation and Implications

• Performing BAL modifies the appearance of lung tissue on ultrasound and X-ray images in adult horses, leading to increased scores that suggest abnormality after BAL even if present before.
• This implies that BAL itself causes imaging changes, such as fluid accumulation or mild inflammation, that can be detected by these methods shortly after the procedure.
• Clinicians should be cautious interpreting lung imaging done soon after BAL, as these changes might be procedure-related rather than due to worsening or the presence of disease.
• When diagnosing or ruling out EAS or other diseases, timing of imaging relative to BAL should be taken into account to avoid misleading conclusions.

Conclusions

• Bronchoalveolar lavage significantly changes lung ultrasound and radiographic appearances in horses being evaluated for EAS.
• Recognizing these BAL-induced changes is critical for accurate clinical interpretation of lung imaging.
• Future guidelines may need to recommend optimal timing of imaging relative to BAL procedures to ensure correct diagnosis.